1. Field of the Invention
The present invention relates to a numerical controller, and particularly relates to a numerical controller having a speedup function by order change or redistribution of a remainder step in a fixed cycle.
2. Description of the Related Art
Conventionally, an example of an operation pattern of hole drilling that is performed using a numerical controller includes a deep hole drilling cycle shown in FIG. 10. This hole drilling cycle performs the following operations.
Operation 1: a drill 2 is fed by a cutting depth q at a specific cutting speed.
Operation 2: the drill 2 is returned to a return point from an end point of Operation 1 by fast feed.
Operation 3: for the next cut, the drill 2 is fed by the fast feed from the return point to a position located before the previous cut endpoint (in Operation 1) by a return amount d (that is set using a parameter or by setting).
Operation 4: the drill 2 is fed by an amount d+q from the end position of the fast feed at the specific cutting speed.
Operation 5: Operations 2 to 4 are repeated.
Operation 6: when the drill 2 reaches a hole bottom during the cut, the cut is ended.
Operation 7: the drill 2 is returned to the return point by the fast feed.
It is possible to perform the above-described deep hole drilling cycle by a command using the following codes.
G83 Xx Yy Zz Rr Qq Ff;
In the above command, each of x, y, z, r, q, and f indicates a data value, X and Y indicate coordinates of a position on an XY plane where hole drilling is performed, Z indicates a coordinate of a position of the hole bottom in the hole drilling, R indicates a coordinate of a position of the return point, Q indicates the cutting depth, and F indicates a feed speed.
The deep hole drilling cycle is used when a deep hole is formed in a workpiece, and is characterized in that the deep hole is formed by intermittently performing cutting feed up to the hole bottom while chips are discharged to the outside.
As a method for reducing execution time of the fixed cycle described above, it is conceivable to change the cutting depth. For example, in a technique disclosed in Japanese Patent Application Laid-open No. 2000-105606, the number of times of a cut operation is reduced by increasing the cutting depth, and the execution time is thereby reduced.
In the case where, e.g., the number of times of the cut operation is not changed when the cutting depth is increased by using the technique disclosed in Japanese Patent Application Laid-open No. 2000-105606, a problem arises in that, instead of reducing the execution time, the execution time is increased correspondingly to an increase in the distance of a fast feed operation. FIG. 11 shows the operation in the case where the cutting depth is increased from the setting in FIG. 10 by a.
The total of the movement distance of the cutting of each of the operation of the deep hole drilling cycle in FIG. 10 and the operation of the deep hole drilling cycle in FIG. 11 is 2q+q′+2d. However, the total of the movement distance of the fast feed in the case of FIG. 10 isq+(q−d)+2q+(2q−d)+(2q+q′)=8q+q′−2d, while the total thereof in the case of FIG. 11 is(q+a)+(q+a−d)+2(q+a)+(2(q+a)−d)+(2q+q′)=8q+q′−2d+6a, and it can be seen that the movement distance is increased by 6a by increasing the cutting depth by a, and the execution time is increased correspondingly.